1. Field of the Invention
The present invention relates to booties or liners for alpine ski boots.
2. Description of Background and Relevant Information
Liners of ski boots are generally formed by two major methods of manufacture, namely: sewing and foam injection.
The manufacture of booties by foam injection in molds in itself constitutes significant progress with respect to the manufacture of liners by sewing, by virtue of the fact that the injection limits the costs of manual labor, manipulation, etc., and makes it possible to obtain an almost finished inner boot immediately after the last injection phase of the foam. On the other hand, the booty made by injection molding likewise makes it possible to form a technically more comfortable product because it adapts better to the anatomy of the foot in the ski boot.
Various methods of manufacturing inner boots by foam injection have formed the object of patents such as French Patent No. 22 21 092 to PALAU, French No. 20 47 650 to HUMANIC or French Patent No. 24 93 112 to SALOMON.
The material utilized to form these inner boots out of foam is generally a polyurethane foam generally having open cells. This structure having open cells however, has the disadvantage of absorbing water or humidity which, either from accidental entry of snow or even simply from the condensation of moisture on the interior of the shell of the ski boot. This disadvantage renders such inner boots relatively non-sealable to the feet of skiers.
It is to overcome this type of inconvenience that Applicants have developed a process of manufacturing taught by French Patent No. 24 93 112 in which one utilizes a inner boot made of films of polyurethane of a thickness equal to approximately 50 microns having the ability to stretch approximately a minimum of 400% which covers the exterior surface of the inner boot to which it thus provides a sealing skin situated over its entire outer periphery. However, the manufacture of such a inner boot is relatively expensive. In effect, the manufacture of this outer inner boot made of films of polyurethane is subject, on the one hand, to extensive manufacture times and positioning on the mold which requires a certain dexterity and, on the other hand, to material expenses which are substantial due to the specificity and to the characteristics of such a polyurethane film. The present invention seeks to form a inner boot for a ski boot having the same technical and sealing advantages as inner boots made of films of polyurethane while eliminating the disadvantages of manufacture and use of the latter.